Mounting of hardware on axial flow compressor casings



p 1967 R. H. BOSTOCK, JR

MOUNTING OF HARDWARE ON AXIAL FLOW COMPRESSOR CASINGS Filed July 29, 1965 United States Fatent O 3,313,475 MGUNTING GE HARBWARE N AXIAL FLGW CUMPRESdGR CASINGE:

- ylance H. Bostock, lira, Qincinnati, Ohio, assignor to General Electric Qompany, a corporation of New York Iniy 29, 1965, Ser. No. 475,768 Claims. (Ci. 230I14) The present invention relates to improvements in axial flow compressors used in gas turbine engines and more particularly to improvements in mounting various items commonly referred to as hardware on casings of such compressors.

Recent innovations in the design of axial flow compressors employed in gas turbine engines, particularly those used for the propulsion of aircraft, have been made in order to meet the ever-increasing requirements of high performance operation. Among these innovations is the use of titanium for many structural components including the outer casing of the compressor. Titanium uniquely provides high structural strength with a minimum weight, however, its use also introduces serious problems in the mounting of various items thereon, including so-called hardware items such as pipe line supports and actuators and other controls and accessories components normally associated with or secured to the compressor casings.

This mounting problem stems primarily from the fact that tapping of threaded holes, as would normally be employed for mounting purposes, is a diflicult and expensive operation and even if such holes were provided, undue stress concentrations make their use impractical. Another alternative which is also impractical is to employ a threaded insert which would be force-fitted into a hole in the casing. Unfortunately, titanium does not have sufficient toughness to properly retain such inserts, and even if they are employed, the use of a force fit again introduces stress concentrations which cannot be tolerated.

Beyond the limitations of the material itself, in one preferred type of compressor the outer surface of the casing has, to a large extent, become inaccessible for the provision of conventional mounting pads. This type of compressor employs stator blades which are pivotally adjusted about radial axes. Such adjustment is obtained by providing lever arms secured to each of the stator blades and overlying the outer casing surface. These lever arms and the control elements therefor are so closely spaced that little available room is left for mounting purposes.

One object of the invention is to overcome the problems of mounting hardware items on axial flow compressors having casings formed of titanium or like material which are difiicult or impractical to machine.

Another object of the invention is to provide means for mounting hardware components on axial flow compressor casings of the type having large areas of the casing surface overlaid by stator adjusting elements.

Another and more specific object of the invention is to provide an improved mounting bracket for axial flow compressor casings which will give a greater versatility of design with a minimum of cost and weight.

The present invention is characterized by the provision of an improved bracket construction for use in combination with an axial flow compressor comprising an outer casing advantageously formed of titanium or equivalent metal. The compressor itself preferably comprises a plurality of stator blades which are secured at one end by a bushing projecting through an unthreaded hole in the casing, with a nut threaded over the exterior of the bushing to clamp the bushing in place and thus provide a fixed journal on the casing wall for the stator. Levers attached to the outer ends of the stator overlie the casing and are connected to' control means for adjusting the angular position of the stator levers to thereby obtain maximum performance of the compressor itself. The stator blades are usually arranged in axially spaced rows along the length of the casing with each row normally functioning in combination with a row of rotor blades to form a compressor stage.

The mounting bracket cooperating with this construction comprises one or more bridge portions which may extend from one stator to another. The opposite ends of each bridge portion are in the form of feet, apertured and telescoped over the stator mounting bushings. The nuts which secure the bushings in place are also employed for the dual purpose of securing the mounting bracket feet on the casing. The bridge portion of the bracket is then provided with mounting means for securing hardware thereto. This arrangement is highly advantageous in that a bracket may be selectively secured in several different positions on the compressor casing as best fits the needs for mounting hardware thereon.

The above and other related objects and features of the invention will be apparent from a reading of the following description of the disclosure found in the accompanying drawing and the novelty thereof pointed out in the appended claims.

In the drawing:

FIGURE 1 is an elevation illustrating in outline fashion a gas turbine engine of the type in which the present invention is advantageously embodied;

FIGURE 2 is an enlarged fragmentary elevation of a portion of the axial flow compressor seen in FIGURE 1;

FIGURE 3 is a section taken on line IIIIII in FIG- URE 2;

FIGURE 4 is a section, on an enlarged scale, taken on line IVIV in FIGURE 2;

FIGURE 5 is a perspective view of a bracket seen in FIGURE 2; and

FIGURE 6 is a perspective view of an alternate embodiment of the invention.

For a better understanding of the environment of the present invention, FIGURE 1 illustrates a gas turbine engine 10 comprising an axial flow compressor 12 which ingests air and compresses it to the desired density to properly support combustion of fuel in a combustor section 14. The combustion gases pass through a turbine stage 16 which provides the driving force for the rotor (not shown) of the axial flow compressor 12. The cornbustion gases are then discharged through a tail section 18 and then through an afterburner section 24). These basic engine components are, of course, well known in the art.

The axial flow compressor 12 comprises an outer casing 22 which is usually formed by two semi-cylindrical shells. The compressor 12 further comprises a plurality of stators 24- which are arranged in circumferential rows spaced along the length of the casing 22 (see also FIGURE 4). The stators 24 cooperate with rotor blades within the casing 22 with each pair of rotor and stator rows forming a compressor stage.

Advantageously for high performance engines several compressor stages will be of the so-called adjustable geometry type, in that the stators are pivotally adjustable about axes extending radially of the compressor. Thus it will be seen in FIGURES 2 through 3 that the outer ends of the stators are journaled on the casing 22 and have secured thereto a lever 26 which projects into overlying relation with the outer surface of the casing 22. The several levers 26 of each stage are interconnected by an actuating ring 28 (FIGURE 1). These actuating rings are in turn connected to a common control lever (two may be employed if desired) that is pivotally mounted at 32 and displaced by an actuator 34 in order to simultaneously adjust the stators of each stage connected thereto to provide optimum operation of the axial flow compressor. Such stator adjustment apparatus is more particularly described in co-pending US. patent application Ser. No. 462,688 filed June 9, 1965 and assigned to the same assignee as the present application.

As indicated above, it is both necessary and desirable that various hardware elements, as for example fuel lines,

e supported along the length of the compressor casing 22. In accordance with the present invention the means for mounting such hardware is provided by a bracket 36 (FIGURES 2-5) which will now be described in detail.

The bracket 36 is of generally triangular outline forming a bridge portion 38, having feet 46 at its opposite ends. An aperture 42 is provided in each of the feet 46 and the upper surface thereof is provided with a counterbore 44 which may be either machined or otherwise formed.

This bracket cooperates with the particular means for mounting the outboard ends to provide means for securing hardware to the compressor casing 22. Thus it will be seen that each stator mounting means comprises a bushing 46 having a flange 48 at its lower end. The casing itself is formed with a hole 56 through which the bushing 46 is projected with the flange 48 preferably engaging a counterbored surface 52 on the interior of the casing 22. The lower surfaces of the feet 40 engage counterbore-d surfaces 54 formed on the outer surface of the casing 22 marginally of the holes 50. A nut 56 is threaded over the upper end of the bushing 46 and clamps against the counterbored surface 44 to draw the flange 48 against the counterbored surface 52 thereby firmly securing the insert 46 and one leg 40 of the bracket to the compressor casing. The opposite end of the bracket 36 is secured to the casing 22 in the same fashion by being telescoped over the adjacent bushing 48 in the same row of stators as indicated in FIGURES 2 and 3.

The bridge portion 38 of the bracket 36 is provided with hardware securing means which advantageously take the form of a steel insert 60 pressed-fitted into the central portion of the bridge portion 38 against a lip 61. The bracket 36 is preferably formed of aluminum and the steel insert 60 is employed to provide threads of sufficient strength. As indicated by the phantom outline in FIG- URE 3 a screw 62 is threaded into the insert 60 to clamp a holder 64 thereon, the holder providing means for supporting a tube 1 running along the length or tangentially of the compressor casing 22.

Preferably the bracket 36 is of the triangular configuration illustrated wherein the bridge portion 38 tapers down to a minimum height at the feet 40 and its undersurface is relieved so that bearing surfaces on the feet need be machined only at the points of engagement with the counterbores 54 formed on the casing 12 marginally of the holes 50. It is also advantageous that the height of the bridge be below the level of the outer ends of the stators to minimize the over-all cross sectional outline of the compressor. However, it would also be possible that the bridge portion be sufficiently high to span over one or more of the stators. Likewise if it is desired to secure a larger piece of hardware to the compressor casing, the alternate embodiment of FIGURE 6 may be employed wherein two bridging portions 38 are provided and are joined by a common foot portion 40. In FIGURE 6 corresponding portions are identified by like reference characters without specific description.

Other variations in the specific constructional details herein shown will be apparent to those skilled in the art and the scope of the present inventive concepts is therefore to be derived solely from the following claims.

Having thus described the invention, what is claimed as novel and desired to be secured by Letters Patent of the United States is:

1. A mounting bracket used in combination with an axial flow compressor of the type comprising,

a shell-like cylindrical casing,

a plurality of stator blades arranged in circumferential rows along the length of the compressor,

said casing having holes therethrough and a bushing projected through said holes to provide means for mounting the outboard end of each stator blade, said bracket comprising,

a bridge portion terminating at each end in a foot,

each foot being apertured and telscoped over a stator mounting bushing, common means securing each foot portion and the bushing over which it is telescoped to said casing, and

clamping means carried by said bridge portion for the securing of hardware thereto to thus mount the hardware on the casing.

2. A mounting bracket used in combination with an axial flow compressor of the type comprising,

a shell-like cylindrical casing,

a plurality of stator blades arranged in circumferential rows along the length of the compressor,

said casing having holes therethrough and a bushing projected through said holes to provide means for mounting the outboard end of each stator blade, said bracket comprising a bridge portion terminating at each end in a foot,

each foot being apertured and telescoped over a stator mounting bushing,

each bushing over which a foot is telescoped having a flange engaging the inner surface of said casing and a nut threaded over the outer end thereof and engaging said foot to provide common means for securing each foot and the bushing over which it is telescoped to said casing, and

clamping means carried by said bridge portion for the securing of hardware thereto to thus mount the hardware on the casing.

3. A mounting bracket used in combination with an axial flow compressor of the type comprising,

a shell-like cylindrical casing formed of titanium,

a plurality of stator blades arranged in circumferential rows along the length of the compressor,

said casing having holes therethrough and bushings respectively projected through said holes to provide journal means for mounting the outboard ends of the stator blades,

said bracket comprising a bridge portion of generally triangular outline, terminating at each end in a foot, each foot being apertured and telescoped over a stator mounting journal bushing,

the upper surface of each of said feet being counterbored to provide a bearing surface marginally of the aperture therethrough, each bushing over which a foot is telescoped having a flange at its inner end engaging the inner surface of said casing, the inner surface of said casing being counterbored to provide an accurate bearing surface marginally of said hole for said flange a nut threaded over the outer end of said bushing and engaging the counterbored surface of said foot to provide common means for securing each foot and the bushing over which it is telescoped to said casing, and

clamping means carried by said bridge portion for the securing of hardware thereto to thus mount the hardware on the casing.

4. A mounting bracket as in claim 3 wherein the bracket comprises two bridge portions in end-to-end relationship joined by a common foot.

5. A mounting bracket used in combination with an axial flow compressor of the type comprising,

a shell-like cylindrical casing formed of titanium,

a plurality of stator blades arranged in circumferential rows along the length of the compressor,

said casing having holes therethrough and bushings resaid bracket comprising a bridge portion of generally triangular outline terminating at each end in a foot, 5

each foot being apertured and the two feet being telescoped over the stator mounting bushings of adjacent stators in one of said rows,

the upper surface of said feet being counterbored to provide a bearing surface of limited radial extent 1 marginally of the aperture therethrough,

each bushing over which a foot is telescoped having a flange at its inner end, engaging the inner surface of said casing, the inner surface of said casing so engaged being counterbored to provide an accurate 1 bearing surface marginally of said hole for said flange, the opposed outer surface of said casing also being counterbored to provide an accurate bearing surface marginally of said hole for engagement by said feet, a nut threaded over the outer end of said bushing and engaging the counterbored surface of said foot to provide common means for securing each foot and the bushing over which it is telescoped to said casing,

the lower surface of said bridge portion being relieved whereby only the undersurface of said feet engage said casing, and

a threaded insert secured to the central portion of said bridge portion to provide clamping means for securing of hardware thereto to thus mount the hardware on the casing.

References Cited by the Examiner UNITED STATES PATENTS 2,819,732 1/1958 Paety 230-114 2,933,235 4/ 1960 Newmann 230-1-14 3,079,128 2/1963 Borge 25378 FOREIGN PATENTS 1,111,358 10/1955 France.

DONLEY J. STOCKING, Primary Examiner. 20 H. F. RADUAZO, Assistant Examiner. 

1. A MOUNTING BRACKET USED IN COMBINATION WITH AN AXIAL FLOW COMPRESSOR OF THE TYPE COMPRISING, A SHELL-LIKE CYLINDRICAL CASING, A PLURALITY OF STATOR BLADES ARRANGED IN CIRCUMFERENTIAL ROWS ALONG THE LENGTH OF THE COMPRESSOR, SAID CASING HAVING HOLES THERETHROUGH AND A BUSHING PROJECTED THROUGH SAID HOLES TO PROVIDE MEANS FOR MOUNTING THE OUTBOARD END OF EACH STATOR BLADE, SAID BRACKET COMPRISING, A BRIDGE PORTION TERMINATING AT EACH END IN A FOOT, EACH FOOT BEING APERTURED AND TELESCOPED OVER A STATOR MOUNTING BUSHING, COMMON MEANS SECURING EACH FOOT PORTION AND THE BUSHING OVER WHICH IT IS TELESCOPED TO SAID CASING, AND CLAMPING MEANS CARRIED BY SAID BRIDGE PORTION FOR THE SECURING OF HARDWARE THERETO TO THUS MOUNT THE HARDWARE ON THE CASING. 